The Full Picture

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global, and employ observing techniques from in situ

to remote sensing. Most significant from an architect’s

perspective is that GEOSS component systems do not

have common management.

The wide diversity and essential independence of

GEOSS component systems calls for a particular style

of systems architecture: a style that emphasizes inter-

operability. Systems are interoperable when their

differences are not a barrier to accomplishing a task

that spans those systems. In the wildland fire scenario,

real-time fire warnings must be interoperable with

routine monitoring and background maps, and alert-

ing systems must be interoperable across a range of

communications media.

Interoperability among diverse systems is base on

separate systems interoperating through standard inter-

faces and other interoperability arrangements. Support

for standardized arrangements is the basis for interop-

erability among credit card systems, for example.

At the system of systems level in GEOSS, interop-

erability allows each system to operate within its own

mandate, while also contributing synergistically to

serve global goals. At the inter-system scale, interop-

erability allows systems to interoperate even though

they are developed and operated independently. At the

scale of a single system, interoperability means that a

system is constructed from modular components.

Such a modular system is more robust, more easily

changed, and better able to use off-the-shelf, less

expensive components.

Given the expansive objectives of GEOSS, it is

necessary that the GEOSS Architecture be embraced

broadly. This means that the GEOSS Architecture must

be mainstream and minimally prescriptive. Ideally, it

should specify just those ‘few things that must be the

same so that everything else can be different’.

The

focus of GEOSS is on how systems work together, and

GEOSS will not constrain how any component system

operates within itself.

Implementing a service oriented architecture

The GEOSS Plan asserts that component systems regis-

tered to GEOSS must share observations and products

with GEOSS as a whole. To enable resource sharing, the

GEOSS Architecture uses a style of systems interoper-

ability known as service oriented architecture (SOA).

A ‘service’ is the basic unit of an SOA. The concept

of a service is straightforward. By analogy to a restau-

rant, a service in operation is like a waiter handling a

dinner order from a customer. Just as a customer is

not expected to give step-by-step instructions to the

kitchen, a service allows clients to precisely specify

their requests, but it does not allow them to specify

the exact procedure for satisfying those requests. This

is very important feature for broad interoperability.

Clients have no more control than necessary, and need

not be concerned with the details of execution.

The GEOSS Architecture is most evident at the points

of interoperability among the various systems

pushpins and grease pencils. However, use of digital mapping is

becoming more widespread. Mapping systems from different

vendors are now highly interoperable, and telecommunications

components are also becoming more interoperable.

A major challenge for GEOSS is to tackle interoperability barri-

ers specific to Earth observations: arranging for open and rapid

data sharing; combing observations from different sources; turning

data into information through models and other analysis tools;

arranging for rapid acquisition of observations as events unfold,

and so on. GEOSS Architecture principles, the GEOSS

Clearinghouse and the adoption of international standards can all

enhance interoperability.

Interoperability enabled by the GEOSS Architecture

Systems architects, like architects in other fields, are concerned

with designing ways to fit components together to attain a larger

objective. Just as a buildings architect may design a city with

diverse components such as housing, factories and offices, the

architects of GEOSS must accommodate diverse components.

GEOSS component systems encompass many scientific disci-

plines. The components range from primary data collection

systems to systems for the creation or distribution of information

products. The component systems span scales from national to

European forest fire information system

A standardized map showing the critical area of a wildland fire.

Maps like these enable tactical planning for warning, evacuation and fire

management

GEOSS C

OMPONENTS

– O

BSERVING

YSTEMS